Fastener die member, panel and fastener assembly and method of installing a fastener

ABSTRACT

The present invention relates to an improved die member, panel and fastener assembly and method for installing a fastener into a panel. The die member has a pair of opposed clinching lips protruding from an end face. The opposed clinching lips have a contact face that narrows as it approaches the opposed ends of the contact face and sidewalls that are angled with respect to vertical. The lips, due to the dual angles, substantially and simultaneously drive panel metal into fastener grooves both longitudinally and laterally. The fastener and panel assembly have panel metal deformed into the fastener grooves resulting in generally wedge-shaped portions of panel metal in the opposed ends of the fastener grooves.

1. This application claims the benefit of U.S. Provisional ApplicationNo. 60/083,578, filed on Apr. 30, 1998.

BACKGROUND OF THE INVENTION

2. The present invention relates to die members, panels and fastenerassemblies and methods for the installation of fasteners into aworkpiece such as for example panel metal. More particularly, thepresent invention relates to an improved die member and method ofinstallation that provides a better fastener installation and has a muchlonger life than previous die members. The main objective of the diemember of the present invention is to reduce the stress on and breakageof the die member that was experienced by conventional die members, andto push more metal into the groove of the fastener to provide a moresecure attachment.

3. The die member of the present invention is used in a fastenerinstallation process shown generally in for example U.S. Pat. No.4,630,363. The die member typically sits below the panel into which afastener is to be installed and is mounted in the bottom platen of apress. An installation head which holds the fastener to be installed ismounted to the upper press platen and positioned on the other side ofthe panel. When the press closes, the installation head drives thefastener into the panel and the die member causes the panel to bedeformed into the locking grooves and around the ends of the fastener.

4. One difficulty with standard die members is that the die members canbreak during the installation process. This results in a badinstallation in the panel and the need to stop the press to replace thedie member. As will be appreciated by those of ordinary skill in theart, when a press is shut down the cost in lost production time can beconsiderable. Therefore, a die member that has increased life willresult in less downtime and increased production capabilities for eachpress.

SUMMARY OF THE INVENTION

5. The present invention overcomes the above difficulties experienced instandard die buttons and fastener and panel assemblies. The die buttonof the present invention has an end face with a pair of opposedclinching lips which protrude from the end face. The clinching lips aregenerally parallel to one another and have a generally flat end face forengaging a panel to which a fastener is to be installed. The clinchinglips include a base which is integral to the end face of the die memberand an outer sidewall which joins the end surface and the base. The endsurface has a mid-point and opposed ends with the end surface beingwider at the mid-point than at the ends and the base is wider than theend surface. The die button is used to attach a fastener having opposed,parallel grooves to a panel metal. The grooves have a base andsidewalls. The die member generally mates with these grooves and drivespanel material into these grooves to fill the grooves. The configurationof the clinching lips of the die member is such that the panel metal isplowed from adjacent the mid-point to the sides of the groove and to theends of the groove to completely fill the groove and still maintain thedie button integrity.

6. In one embodiment, the die button end surface narrows gradually fromabout the mid-point to the opposed ends. In another embodiment the endsurface begins to narrow gradually a spaced difference on either side ofthe mid-point.

7. The invention further teaches a novel panel and fastener assemblywhich comprises a fastener having generally parallel channel-shapedgrooves with each groove having a bottom wall, opposed sidewalls, amid-point portion and opposed open end portions. The panel isplastically deformed into these grooves to define a mating region of thepanel. The mating region is forced against the bottom wall and opposedside walls of the grooves. The mating region defines a panel bottomsurface adjacent the bottom wall, a first side surface adjacent one ofthe opposed sidewalls and a second side surface adjacent one of theother opposed sidewalls. The first side surface has a greater width atthe opposed open end portions than at the mid portion.

8. In one embodiment, the first side surface width of the panel metalincreases from about the mid-point to the opposed open end portion. In asecond embodiment, the first side surface of the panel metal has agenerally uniform width along a middle portion of the first side surfaceadjacent the mid portion and opposed outer portions which are generallywedge-shaped.

9. The present invention also discloses a method of attaching a fastenerto a deformable metal panel by locating the panel on a die member havingspaced generally parallel projecting lips adapted to be received in thefastener grooves of the fastener. A fastener is located opposite thepanel with the fastener grooves aligned with the die member lips. Thefastener and panel are driven together driving the die member lips intothe fastener grooves shearing a slug and deforming portions of the panelinto the fastener grooves. The die member lips substantiallysimultaneously drive the panel portions in the fastener grooveslongitudinally toward the open end portions of the grooves and laterallytoward the sidewalls of the grooves.

10. Other advantages of the present invention will be readilyappreciated as the same becomes better understood by reference of thefollowing detailed description when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

11.FIG. 1 is a perspective view of the die button, panel and fastener ofthe present invention;

12.FIG. 2 is a top view of the die button of FIG. 1;

13.FIG. 3 is a cut-away view taken along lines 3-3 of FIG. 2;

14.FIG. 4 is a cut-away view taken along lines 4-4 of FIG. 2;

15.FIG. 5 is a cut-away view taken along lines 5-5 of FIG. 2;

16.FIG. 6 is a top view of a second embodiment of the design button ofthe present invention;

17.FIG. 7 is a cut-away view taken along lines 7-7 of FIG. 6;

18.FIG. 8 is a cut-away view taken along lines 8-8 of FIG. 6;

19.FIG. 9 is a cut-away view of the die button of FIG. 2, panel andfastener of the present invention; and,

20.FIG. 10 is a top view of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

21.FIG. 1 shows a pierce nut 20 of the type used with the die member 24of this invention, ready for installation in a panel 22 by die member24. The illustrated pierce nut includes a central rectangular pilotportion 26 having a flat top piercing face 28, end walls 30 generallyperpendicular to the top face 28 of the pilot and integral flangeportion 32 on opposed sides of the pilot. The flange portions 32 includetop panel bearing faces 34 spaced below the plane of the top face 28 ofthe pilot, and parallel grooves 36 on opposed sides of the pilot 26 isextending perpendicular to the end walls 30 of the nut.

22. It will be understood that “top” and “bottom” are relative terms andare used herein for purposes of description only. Further, the piercenut, panel and die member are arranged in the drawings to illustrate themethod of forming the nut and panel assembly of this invention. Inactual use, the die member 24 will generally be the lower or bottomelement and the pierce nut is moved downwardly by the pierce nutinstallation head to form the nut and panel assembly. As will beappreciated by those of ordinary skill in this art, a pierce nut isgenerally installed by a pierce nut installation head in a die pressassembly. The panel may be simultaneously formed in the die press,particularly in automotive applications, and several pierce nuts may besimultaneously installed in the panel, in one stroke of the press. FIG.1, however, illustrates a commercial application, regardless of whetherthe pierce nut 20 is located above or below the die member 24, with thepanel 22 located therebetween.

23. The parallel grooves 36 each include an inner side wall 38, a bottomwall 40 and an outer side wall 42. In the disclosed embodiment of thepierce nut 20, the grooves are re-entrant, wherein one or both of theinner and outer side walls, 38 and 42, respectively, are inclinedinwardly, toward the longitudinal axis of the groove, to form arestricted groove opening. The re-entrant grooves entrap the panel metaldeformed into the grooves substantially improving nut retention, asdescribed in U.S. Pat. No. 3,648,747, which is included herein byreference.

24. The disclosed pierce nut 20 includes a central threaded bore 44having an axis generally perpendicular to the top face 28 of the pilot26. In the disclosed embodiment of the pierce nut, the pilot alsoincludes side walls 38 perpendicular to the top face 28 of the pilot,and the sides 48 of the flanges are truncated primarily to reduce theweight or mass of the pierce nut. The bottom face 50 of the pierce nutis preferably flat and generally parallel to the top face 28 of thepilot. The bottom face 50 is engaged by a plunger of an installationapparatus or head (not shown) to form the nut and panel assembly; seealso U.S. Pat. Nos. 3,108,368 and 3,969,808, which disclose suitableinstallation heads which may be utilized to form the nut and panelassembly of this invention. Both of the above-referenced patents areassigned to the assignee of the present application and the disclosuresare incorporated herein by reference.

25. The die member of the present invention is shown generally at 24 inFIG. 1 and the face of the die member 24 is shown in FIG. 2. The diemember 24 has a body 25 and an end face 64. The end face is shown inFIG. 2. An opening 52 is formed for receipt of the slug formed by thepierce nut 20 cutting through the panel 22. The face 64 has lips 60 and62 which drive panel metal into the grooves 36 of the fastener 26 andalong end faces 30. The lips 60 are staking lips which keep the fastenerfrom moving with respect to panel 22 when the fastener 20 is installed.The staking lips 60 are generally parallel to one another. The lips 62are clinching lips which clinch the panel metal into the grooves of thefastener 20. The end surface 61 of lips 60 and 62 is generally flat.

26. The lips 62 are angled with respect to the vertical and horizontalaxes. As illustrated in FIGS. 3 through 5, the sides of the lips 62 areangled with respect to the die vertical axis between 10°and 20° andpreferably at about 15°, see arrows a-a, in FIG. 3. As illustrated inFIG. 2, the sides of the lips 62 are also angled with respect to thehorizontal axis between 1°and 10°and preferably at about 5°, see arrowsb-b in FIG. 2. The angle of the lips 62 in two planes facilitatesenhanced packing of metal into the groove of the fastener 20, which willbe discussed in greater detail below.

27. The lips 60 are angled with respect to the contact face 61 between40°and 50°and preferably at about 45°. The inner corners 68 of the diemember lips are radiused and the outer corners 70 of the lips are angledat approximately the same angle to the vertical as lips 60. The contactface 61 of the lips 60 and 62 is generally flat to provide a greatersurface area to force panel metal into the grooves 36 and provide alarger surface area to reduce the contact pressure acting on the lips60, 62.

28. The packing of the metal into the grooves 36 is illustrated in FIGS.3 through 5 and FIG. 10. The illustration in FIG. 3 is a section takenalong lines 3-3 of FIG. 2; FIG. 4 is a section taken along lines 4-4 ofFIG. 2 and FIG. 5 is a section taken along lines 5-5 of FIG. 2. Asillustrated in FIG. 3, the lip is wider than the lip in FIGS. 4 and 5.The lip 62 is widest at the midpoint of the lip, at line 3-3, andbecomes narrower as it extends to the corners. This narrowing of thelips 62 causes metal to be plowed from the mid-point 80 to the ends 82of the groove 36 of the fastener 20 to better fill the groove, see FIG.10, arrow C. The angle of the lips with respect to vertical alsofacilitates the movement of the metal within the groove and plows metalfrom the center to the outer side of the groove, see FIG. 10, arrow D.As illustrated, the wider lip at section 3-3 leaves less room betweenthe lip at 3-3 and the walls 38 and 42 of the fastener 20. Because thereis less room, the panel metal at this location must be displacedelsewhere and the path of least resistance is to the wider areas towardsthe ends of the lips, i.e., sections 4-4 and sections 5-5. Therefore,the metal is plowed or pushed away from the midpoint of the lip to fillthe entire groove 36.

29. The panel 22 includes a mating region 72 which is driven into matingcontact with grooves 36 by lips 62. The mating region 72 includes apanel bottom 74, first side surface 76 and second side surface 78. Asillustrated, the panel 22 in the mating region 72 is forced under theinwardly extending sidewalls 38 and 42, in other words, the grooves 36are filled with the mating region 72.

30. The cross-sections in FIGS. 3 through 5 are taken along thecorresponding lines in FIG. 2 to illustrate the increasing width of thefirst side surface 76 as its distance increases from the generalmidpoint 80 of groove 36, to the opposed ends 82 of groove 36. In thepreferred embodiment, a flat surface 79 is provided for facilitatingtooling and dimensioning of the die button. Other than the flat surface79, the sidewall 62 is angled.

31. In use, the fastener is fed into an installation head, such as forexample, the installation head disclosed in U.S. Pat. No. 5,487,215. Theinstallation head is mounted to the platen of a press with the diemember mounted to the opposite platen. Sheet metal 22 is mounted uponthe die member and the press closes, driving a fastener from theinstallation head into the panel and the die member. The lips 60 and 62are driven into the grooves 36 and adjacent end walls 30 deforming metalinto the grooves 36 and along side the end walls 30. A slug is piercedfrom the panel by the end face 28 of the pilot and the pilot 26 isreceived through the pierced panel opening.

32. The stress on typical die member lips is about 600,000 to 700,000PSI. A typical die member with forces in this range is disclosed in U.S.Pat. No. 4,630,363. In previous die members manufactured by applicant,the contact face of the clinching lips were about 0.019 inches wideresulting in the potential for broken die members because of the highforces per square inch. In the disclosed embodiment, the contact face ofthe clinching lips at the midpoint is wider, approximately 0.050 inches,to reduce the forces being applied. Additionally, the height of the lips60, 62 is less to better withstand the forces and facilitate filling ofthe groove 36. Overall, with the angled lips, flattened end faces andheight reduction, the stresses on the lips have been reduced to about107,000 PSI which greatly extends the life of the die member. A furtherbenefit is the reduction of the bending stresses on the clinch lips 62.By reshaping the clinch lips 62, the bending stresses are reduced by31,600 PSI, from about 152,000 PSI to about 121,000 PSI.

33. It should be appreciated that the dimensions provided areapproximate and are for the disclosed die button to obtain optimumperformance. The die button dimensions may change as a result of thevolume of the metal into which the fastener is installed and may changedepending upon the width of the groove 36 in fastener 20.

34.FIG. 9 illustrates a cross-section of the die button 24 as theinstallation of the fastener to the panel completed. As illustrated, theslug 69 has been cut from the panel 22 by the pilot portion 26.

35.FIG. 10 is a top view of FIG. 9 illustrating the fastener 20 attachedto a panel 22 on top of die member 24. The arrows C and D illustrate theflow of metal in both the lateral direction D and longitudinal directionC of the groove 36. As can be seen, the metal flows in two directionsfrom the mid-point 80 out to the ends 82.

36. Applicant has found that the die button of the first embodiment ispreferably used in low carbon, low strength stamping material. Thesecond embodiment discussed below is preferably used in high strength,low alloy stamping material.

37. With reference to FIGS. 6-8, a further embodiment of the die buttonof the present invention is illustrated at 85. In this embodiment, theclinching lips 62 are angled in the same maimer as the clinching lips 62of the previous embodiment. However, in this embodiment, the lips 62 areangled at a spaced distance from the mid-portion 84 of the lip 62. Ascan be seen in this embodiment, there is a wider mid-section 86 than inthe previous embodiment. In the disclosed embodiment, the mid-section 86is approximately ⅝inches in length. The length of the mid-section 86will vary depending upon the fastener size that is used. The width ofthe contact face 61 in this embodiment is approximately 0.059 inches. Aswith the previous embodiment, the dimensions may change depending uponthe volume of the metal and the size of the groove 36. In thisembodiment, the die button 85 has inclined surfaces 88 and 90 which plowmetal in the same manner as the previous embodiment, but because of thewider and longer mid-section 86, less metal is plowed. It has been foundthat with a thicker section on the lips 62, there is lower stresses inthe fastener. With greater amounts of metal being plowed, the fastenermight be deflected to accommodate the metal being moved, which is notacceptable in many applications.

38. In the preferred embodiment, a break-away angle 92 is provided. Thebreak-away angle 92 is provided to avoid sticking of the lip 62 in thepanel. By providing the break-away angle of about 7°along themid-section 86, the lips 62 can freely release from the panel after thepanel has been driven into the grooves 36.

39. The invention has been described in an illustrative manner, and itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than limitation.

40. Obviously, many modifications and variations of the presentinvention are possible in light of the above teachings. It is,therefore, to be understood that within the scope of the appendedclaims, the invention may be practiced otherwise than as is specificallydescribed.

What is claimed is:
 1. A panel and fastener assembly comprising: afastener having generally parallel channel-shaped grooves, each groovehaving a bottom wall, opposed sidewalls, a mid-portion and opposed openend portions; said panel being plastically deformed into said grooves todefine a mating region of said panel, said mating region being againstsaid bottom wall and said opposed sidewalls defining a panel bottomsurface adjacent said bottom wall, a first side surface adjacent one ofsaid opposed sidewalls and a second side surface adjacent the other oneof said opposed sidewalls, said first side surface having a greaterwidth at said opposed open end portions.
 2. The panel and fastenerassembly of claim 1 wherein said first side surface width increases fromabout said mid-portion to said opposed open end portions.
 3. The paneland fastener assembly of claim 1 wherein said first side surface has agenerally uniform width along a middle portion of said first sidesurface adjacent said mid-portion and opposed outer portions which aregenerally wedge-shaped.
 4. The panel and fastener assembly of claim 1wherein said mating region is generally U-shaped in cross-section. 5.The panel and fastener assembly of claim 1 wherein said fastener opposedsidewalls are inclined inwardly to form a restricted groove opening. 6.The panel and fastener assembly of claim 1 wherein said opposedsidewalls and said bottom wall meet at a radiused portion.
 7. The paneland fastener assembly of claim 1 wherein said fastener includes agenerally central pilot portion which cuts a slug from and protrudesthrough said panel.
 8. The panel and fastener assembly of claim 7further including opposed flange portions on opposed sides of said pilotportion, said grooves being positioned between said pilot portion andsaid flanges, said flange having panel bearing faces bearing againstsaid panel.
 9. A method of attaching a fastener to a deformable metalpanel, said fastener having generally parallel channel-shaped grooves,each groove having opposed sidewalls, a mid-portion and opposed open endportions, said method comprising: locating said panel on a die memberhaving spaced generally parallel projecting lips adapted to be receivedin said fastener grooves; locating said fastener opposite said panelwith said fastener grooves aligned with said die member lips; drivingsaid fastener against said panel, thereby driving said die member lipsinto said fastener grooves and deforming portions of said panel intosaid fastener grooves; and said die member lips substantiallysimultaneously driving said panel portions in said fastener grooveslongitudinally toward said open end portions of said grooves andlaterally toward said sidewalls of said grooves.
 10. The method ofattaching a fastener to a deformable metal panel as defined in claim 9 ,wherein said method includes deforming said panel portions in saidfastener grooves laterally to a greater extent as said panel portionsapproach said open end portions of said grooves, forming opposedwedge-shaped bottom walls in said panel portions engaging a bottom wallof said fastener grooves and said sidewalls at said grooves.
 11. Themethod of attaching a fastener to a deformable metal panel as defined inclaim 9 , wherein said method includes deforming said bottom walls ofsaid panel portions laterally from adjacent said mid-portion of saidgrooves, forming opposed wedge-shaped portions extending from adjacentsaid mid-portions of said grooves.
 12. The method of attaching afastener to a deformable metal panel as defined in claim 10 , whereinsaid method includes deforming said bottom walls of said panel portionslaterally from a location spaced from said mid-portion of said grooves,forming opposed wedge-shaped portions adjacent said open end portions ofsaid grooves.
 13. The method of attaching a fastener to a deformablemetal panel as defined in claim 9 , wherein at least one of said grooveside-walls of each of said grooves is inclined inwardly, said methodincluding forming said panel portion laterally beneath said inclinedsidewalls of said grooves.
 14. A method of attaching a fastener to adeformable metal panel, said fastener having generally parallelchannel-shaped grooves, each groove having a bottom wall, opposed sidewalls, a mid-portion and opposed open end portions, said methodcomprising: locating said panel on a die member having spaced generallyparallel projecting lips configured to be received in said fastenergrooves; locating said fastener opposite said panel with said fastenergrooves aligned with said die member lips; driving said fastener againstsaid panel, thereby driving said die member lips into said fastenergrooves and deforming portions of said panel into said fastener groovesagainst said bottom walls of said grooves; and driving said panelportions in said fastener grooves longitudinally toward said open endportions of said grooves and laterally toward said side walls of saidgrooves adjacent said open end portions forming opposed generallywedge-shaped bottom walls in said panel portions engaging said bottomwall of said grooves.
 15. The method of attaching a fastener to adeformable metal panel as defined in claim 14 , wherein said methodincludes deforming said bottom walls of said panel portions laterallyfrom adjacent said mid-portion of said grooves, forming said opposedwedge-shaped portions in said bottom walls of said panel portionsextending from adjacent said mid-portion of said grooves.
 16. The methodof attaching a fastener to a deformable metal panel as defined in claim14 , wherein said method includes deforming said bottom walls of saidpanel portions laterally from a location spaced from said mid-portion ofsaid groove forming said opposed wedge-shaped portions adjacent saidopen end portions of said grooves.
 17. A die member comprising: a bodyhaving an end face; a pair of opposed clinching lips protruding fromsaid end face, said clinching lips being generally parallel to oneanother; said clinching lips having a generally flat end surface forengaging a panel to which a fastener is to be installed, a base which isintegral to said end face and an outer sidewall, said sidewall joiningsaid end surface and said base, said end surface having a mid-point andopposed ends with said end surface being wider at said mid-point than atsaid opposed ends, and said base being wider than said end surface. 18.The die member of claim 17 wherein said end surface narrows graduallyfrom about said mid-point to said opposed ends.
 19. The die member ofclaim 17 wherein said end surface begins to narrow gradually a spaceddistance on either side of said mid-point.
 20. The die member of claim17 further including an opening extending through said body and said endface.
 21. The die member of claim 20 further including inner sidewallsspaced from said outer sidewall, said inner sidewalls positioned aboutsaid opening.
 22. The die member of claim 17 further including a pair ofopposed staking lips protruding from said end face, said staking lipsbeing generally parallel to one another and generally perpendicular tosaid clinching lips.
 23. The die member of claim 22 wherein said stakingand clinching lips are joined at this free end by corners to form acontinuous protrusion.